Are you running the Iron Hands detachment? If not, you should. I'd drop extra armor on everything. They're highly situational and absolutely not worth the points unless maybe on the stormraven. Also, why take combi-gravs on them when you can take full on grav guns or even a cannon or two?
Since you're not going to use the venerable as a gun platform, I'd gear it for close combat with a twin linked heavy flamer and maybe another heavy flamer. That way, if you drop the command squad into the thick of things, the dreadnought can clear any potential mobs that may swarm them or smash nearby vehicles. Personally, I prefer the ironclad because you can stick a chainfist on it which makes penetrating vehicles a lot easier, you get an extra attack, and 13/13/10 makes a difference, but that's if you have the model or you/your opponent don't mind proxying. I also think you can scale the stormraven down a tad and take a multi-melta instead of the typhoons and drop hurricane bolters.
